1. Field of the Invention
The present invention relates to a high-voltage measuring device for detecting a high-voltage.
2. Description of the Related Art
On an accumulator such as a storage battery in an electronic car, a high-voltage measuring device for detecting a high-voltage is provided to protect against the electric overcharge or over-discharge.
As shown in FIG. 1, a conventional high-voltage measuring device is, for example, provided with two resistors 3 and 4 and a voltage measuring circuit 4 which are mounted on a substrate 1, for example, in the form of a printed circuit. Positive and negative terminals of a high-voltage battery 5 are electrically connected to one ends of the resistors 2 and 3, respectively. The other ends of the resistors 2 and 3 are electrically connected to input terminals of the voltage measuring circuit 4, respectively. The resistors 2 and 3 are used for dividing a high-voltage supplied from the high-voltage battery 5, and the voltage measuring circuit detects an electric potential difference between the resistors 2 and 3 which corresponds to the high-voltage.
It is to be understood that large-sized resistors have been used for the resistors 2 and 3 in the conventional device. Those resistors must have high resistances and high-voltage-proof properties since they are used into division voltage.
In addition, there arises another problem of high cost that the size of the substrate 1 must be large enough to make sure that the resistances 2 and 3 and the voltage measuring device 4 are separated from each other for electric isolation even under such high electric potential differences between the resistors and between the resistors and the voltage measuring device.